Compression devices for applying compressive forces to a selected area of a person's anatomy are generally employed to improve blood flow in the selected area. Compression devices that provide intermittent pulses of a compressed fluid (e.g. air) to inflate at least one inflatable chamber in a sleeve are particularly useful. This cyclic application of pressure provides a non-invasive method of prophylaxis to reduce the incidence of deep vein thrombosis (DVT), and the like. These compression devices find particular use during surgery on patients with high-risk conditions such as obesity, advanced age, malignancy, or prior thromboembolism. Patients who have this condition often have swelling (i.e. edema) and tissue breakdown (i.e. venous stasis ulcer) in the lower leg.
In general, compression devices include a sleeve having at least one fluid inflatable pressure chamber progressively arranged longitudinally along the sleeve. A pressure source (e.g. a pump) is provided for intermittently forming a pressure pulse within these inflatable chambers from a source of pressurized fluid during periodic compression cycles. The compression sleeves provide a pressure gradient along the patient's limbs during these compression cycles, which progressively decreases from the lower portion to the upper portion of the limb (i.e. from the ankle to the thigh).
Examples of compression sleeves are disclosed in U.S. Pat. Nos. 4,013,069 and 4,030,488 to Hasty, U.S. Pat. Nos. 4,029,087 and 5,795,312 to Dye, and U.S. Pat. No. 5,626,556 to Tobler et al., all of which are currently owned by Tyco Healthcare Group, LP and are incorporated by reference herein in their entirety. Other examples of compression sleeves are disclosed in U.S. Pat. Nos. 4,696,289 to Gardner et al. and 5,989,204 to Lina.
When compression therapy is administered to a patient, the inflatable pressure chambers of the compression sleeves of the foregoing description may include trapped air. Trapped air changes the volume of a chamber, thus reducing the pressure gradient along the patient's limb during treatment. The shape, weight, and position of a patient's limb will contribute to the size and number of pockets of air formed. An example of compression treatment method is disclosed in U.S. Pat. No. 6,231,532 to Watson et al., which is currently owned by Tyco Healthcare Group, LP, the contents of which we hereby incorporated by reference herein in their entirety.